Why is the ring at such an angle when animated?
To not to have any issues with Rigid Body Simulation remember to always apply Scale and Rotation for your objects - Ctrl+A and also keep in mind that really small objects will behave strangely.

In your case, after applying Scale and Rotation you will need to change ring Mass to something like 1.

Secondly, to increase Rigid Body Simulation time you will need to go to Scene tab and under Rigid Body Cache set the End value to match your Timeline value.